Idempotent
by MandereLee
Summary: The prince impatiently pulled her along, laughing with a glee she couldn't quite understand.


AN: Hey, this is my entry for LingFan day. It just consists of some of my headcanons for them from the time they were growing up together, to when Ling became emperor.

I hope you all enjoy!

Warnings: Corporal punishment... not much else.

* * *

**Idempotent**

When he was five and felt he owned the world, he would climb the steep pillars of the old temple at the edge of Yao Keep, and pretend he could fly. It was a child's dream, but Ling had his age as the perfect excuse, and Xing itself could use more dreamers anyway. His mother would send guards and servants to try to fetch him, because clearly at this point he was as much a danger to himself as assassins, but chubby feet proved to be much better at evading armor-clad guards than initially assumed.

And Ling would climb, high, very high, up to the tiled roofs, the ceramic ring of the tiles sounding wonderful to his ears. And he'd welcome the glowing orb of the sun, with outstretched arms and a toothy grin, as it mushroomed over the horizon.

It was at this point that the perfect lure back to earth would come – sent by his cunning mother, no doubt – taking tiny uncertain steps towards the temple. In her hands was a small bowl of soup, and she would look up at him, at the roof, with wide, glassy eyes.

"Princey, let's eat!" she'd say, her voice small, yet carrying over the distance, most likely because he'd known what she was going to say.

And down there, with miso and Lan Fan, he would forget all the reasons why he wanted to be up at the roofs in the first place.

-o-

The moringa tree outside of Lan Fan's bedroom was prone to shedding. Its leaves streamed down in steady waves, all green and pale gold at this time of year, surfing on the wind that foretold an early monsoon. The moon, whose light would have eased her nervousness was coveted by darkened clouds.

"Should we close the window?" the prince, whose pallet was next to hers, whispered quietly.

Lan Fan nodded, but when the two of them waited one moment too long for the other to get up and close it, she knew that that window would remain open for the rest of the night.

"We shouldn't have asked Grandpa to tell us that scary story."

"I didn't know it was going to be _that_ scary," Ling pouted, tucking his blanket around him more securely. A new gust of wind whistled outside, and they both looked reluctantly at the opened window. "And really, it's not! I mean, not that scary really."

Lan Fan shuddered. Six year olds shouldn't get scared of bedtime stories anymore, should they? Especially six year olds from the warrior clan serving the Yaos! They were the strongest, most fearsome warriors and no _g__uǐ_, not even a _yuān guǐ_ should shake their bones and quake their hearts. Swallowing her nervousness, her eyes sought the young lord again, all caterpillar-like with his small body cocooned in his blankets.

"Don't worry, Princey! I will protect you if it comes!" she whispered to him.

Suddenly his eyes opened wide, all stubborn and offended, and he snaked an arm out of the tight clutches of his sheets, pointing an accusing finger at her.

"I'm the Yao _heir,_ destined to be the emperor one day! _I_ do the protecting around here!" And he jumped from his pallet, zoomed to the window to pull the shutters closed, and just as hurriedly came back down to the floor to wiggle inside Lan Fan's sheets.

"Uh, wrong bed."

"Doesn't matter," he said, weaving small arms around her. Lan Fan didn't miss the way they shivered. "The other one is decoy now!"

And that was how her grandpa found them the morning after.

-o-

The first time Ling met Lan Fan, she had been nothing more than a bundle of bandages and gauze. Well, actually, that had been the _second_ time, because the first time was much worse, when she had worn her parents' blood, but he had only caught half a second glimpse of her then. He didn't count it.

No, the _real_ first time they met, she was lying on a bamboo mat, wrapped in all white, with an old alkahestrist fanning her against the summer heat. He and his mother had only been walking by the soldiers' wing when they met Fu, and his mother began talking in those low tones that signified it was _adult talk_ and _not for three-year-olds_ like him. But he remembered Fu from the other night; a warm, solid brick of a man that had been her mother's comfort as the Daos wrecked havoc on the Yao palace above. And he remembered the confusion and grief as they discovered what remained of the servants' wing, and the bodies, the many bodies he'd glimpsed through his mother's protective fingers over his eyes.

And he remembered Fu yelling, pleading for a doctor, clutching something in the cradle of his arms.

Lan Fan was her name. She was little, like him but smaller, and he wanted to play.

He poked a curious finger at her cheek, her face the only spot uncovered by the bandages. He stole a quick glance back at his mother, still talking with old man Fu at the doorway. The alkahestrist had been summoned to his side to explain some things, and here Ling was, alone with a little child, and two stuffed toy monkeys clinging at his side.

Another poke, and her eyes fluttered open. For a moment, Ling remained still, stunned.

Lan Fan took a shaky breath. "Mama..."

Ling glanced again back at the door, and put a finger to his lips. "Shh... Mama's over there, but don't let her hear you."

Her face scrounged up, her mouth twisting into a grimace so intense. "Oww–"

Ling covered her face with one of his monkeys. "It's alright! My magic monkey will make your ouchies go away!"

"Ling!" his mother's loud voice shouted from the entrance of the room. "What_ in the world_ are you doing to poor Lan Fan?" Ling was snatched off the bed, his monkey tumbling down to the floor, as his mother hauled him away from Lan Fan, who was now howling with an intensity the boy couldn't believe was coming out of her small form. The alkahestrist and Master Fu was buzzing around her, and he could hear them calling for assistance.

"I just wanted to play!" he protested.

"She cannot play! She is injured!" his mother reprimanded, and Ling felt the tears start to bubble out from his eyes.

She summoned her waiting women to help carry him out of the room and back to their apartments. He didn't see the girl for weeks.

-o-

Grandpa said her Mama and Papa were gone, but Lan Fan didn't know where. Sometimes they would go to town, she remembered, and some of Papa's stories were from the capital, so perhaps they went there too. She hadn't seen them since she woke up.

Grandpa held up a bag, and showed her her clothes and her two toys. "Looks all good to you?" he asked. She nodded.

"Alright then, you'll be sharing my room from now on," he smiled gently. "Won't that be fun, you think? You always liked the east side of the palace grounds."

"How about Mama and Papa?"

Grandpa looked at her for a very long time, and sighed. "Lan Fan, they won't be coming back. You remember what I said? About that night?"

Lan Fan nodded. Her parents had fought bravely and honourably and were gone.

Where?

Grandpa sighed again, but picked her up from the bed, handing the brown stuffed monkey she found beside her when she first woke up three days ago. He took her hand, and they walked out of the sick room, and out into the courtyard to cross the palace.

She heard it before she felt it, but everything happened so fast; the only clear thing she remembered was the weight on top of hers, the warmth on her head, and the shrilly laughter repeating "You're all better!" over and over again.

Lan Fan realized she must have been yelling for help, because her grandfather took whatever it was and settled it on the ground.

_It_ turned out to be a boy, only a bit taller than her, with eyes so narrow with smiling that she couldn't see his pupils.

"Don't you remember me? I'm your best friend!" he declared cheerfully, but Lan Fan had never seen him before.

"Lan Fan, this is Prince Ling Yao," Grandpa patted her shoulder encouragingly. "He is a kind, gentle child, who is very compassionate and... caring." She hardly heard him amidst the prince's ministrations: a pinch to her cheek ("Oh, how soft!"), a pull on her bangs ("What shiny hair!"), the lifting of her dress ("Let me see your battle scars!").

When he calmed down, Grandpa pointed to the monkey in her arms. "He's the one who gave you that."

Oh. Lan Fan looked at the boy, and held out the monkey to him.

"Huh, what? I don't want that. I want to play!" And he pulled at her arms, towards the center of the courtyard, where she saw for the first time, a group of waiting women and serving men.

"Wait, hold on!" Grandpa called after them, before they'd gotten very far. He turned around to the alkahetrist who had been walking along with them. Lan Fan vaguely heard her say, "The sun would be good," and "She'd been indoors too long" and the rest faded before she caught them. Then her grandfather turned back to them, and nodded. "Alright. For fifteen minutes, then Lan Fan needs to rest again."

The prince impatiently pulled her along, laughing with a glee she couldn't quite understand.

-o-

The pain in her back when the bamboo first hit did not sting immediately, did not steal her breath like her Grandpa's practiced punches. Rather, it was a slow kind of welcome into hell, the strip of flesh initially rendered numb. But then the heat came. And then the blast of ache, doubling half a second later when the bamboo came down again, striking at an angle.

The master servant hit her back again, then again. He was not going to show mercy. Not when the Chu ambassador stood only paces away, watching the beating with a self-satisfied air and a futile poker face.

No, she had not broken the axle to his wagon, not planned for the carriage to tip over and deposit him onto the paved ground, but he'd come storming back into the palace, clutching a broken ankle and claiming that it could have been his neck. Nobody in their right mind could out the young prince; a disclosure like that could mean war, a little prank by an eleven year old a deliberate political threat when it came from nobility.

Nobody spoke the prince's name.

Her Grandpa had not stopped her when she confessed it was her, and begged the ambassador for forgiveness for her naivety, her stupidity.

The Chu dignitary was kind. Only a hundred lashes. At least he didn't put her to death.

Lan Fan had lost count at about twenty or so. Her back felt like a hive of bees, buzzing with agony; she'd always had a high threshold for pain, but she knew this was testing that to new heights. Her fingers dug into the muddy soil below her, dirt packing into her nails though they were short. She hardly felt the stick come down; she could only recognize it in the strip of her back that would sting with heat, and the breaking of skin that accompanied it.

Nobody said anything. They just watched, and most of the people at the palace were watching. Chu had made such a flourish of coming in.

She only noticed the blood trickling down her arms when the soil changed hues.

Lan Fan tuned it out and everything else with it. She only remembered the dimming sun, the growing shadows around her vision, when it was all over. Then Chu's face as he kneeled over her, a small smile on his lips as he dropped something on her limp palm.

A button covered in blue silk with silver embroidery. From the young lord's cuff?

He had known.

-o-

Ling didn't know what he went there to say, what he _could_ even say after yelling himself hoarse at his mother, at master Fu, at everyone who just _stood there and watched_. He came too late, finding the courtyard blanketed in cold, hushed whispers as Lan Fan's body was taken to the infirmary.

She sat now at the bed, her torso wrapped in bandages tainted with red fluid at the back. Her face was white and drawn out, but her look was expressive, so open. And her eyes were dry. Ling ignored the pang of jealousy that told him if he had been given a hundred lashes, he would have cried by the third.

"What's wrong with you?" he found the words out of his mouth before he had planned to say them.

Lan Fan was taken aback. She blinked, then looked down, a light blush tinting her cheeks. He was surprised her body even found blood to do that.

"Young master... I'm... I don't know," she whispered.

Somehow her deference and her hesitance made him angrier.

"You don't know?" he spat. There was a curdling in his blood, and he could feel anger seeping out of him, as if his skin could not contain how much of it was inside. "How could you not know?"

"I..." She searched his face, trying to find a way to answer his question, and she must have found nothing, because she looked back down, shame written all across her face. "I'm sorry. What is it you want from me, Young Lord?"

"Oh, stop it, Lan Fan!" he yelled, his voice catching, his throat feeling like sandpaper. "I want nothing from you, you idiot! Because you're already so goddamned perfect, and I _hate_ it!" He had clutched his hands into tight fists, raised as if to strike – because damn it, _why did she have to do that? _And she looked back at him like rabbits did when they felt trapped.

Then she cried.

Sobbed like he had never seen her done, even when she'd broken both her wrists during a particularly intense practice session. And he felt the anger drain from him, revealing the truth at its core – the guilt that pooled at his center, and the childishness that caused him to ignore it, to attribute it to something so false, that really he wondered which one of them was the real idiot.

Her sobs racked her small body, her voice sad and wrenching.

The horror hit him so hard that he almost wept too. Instead, he took her in his arms and for the first time that day, did something right.

"I'm sorry," he whispered, his voice and arms shaking. "I'm so sorry, Lan Fan." Her back was a patchwork of red even through the bindings, and he felt himself choked with regret and second-hand pain.

And he realized, after seeing her unfazed by a hundred lashes, yet broken down by his words, that it was never her he'd been angry with. It was never with the others, who had watched and did nothing.

-o-

The abyss of Greed's mind was a cesspit of tar and blood, and by the third month, Ling thought he would go mad with all the black and red. If Greed let him out more often, he probably would not mind half so much, but at this rate, sometimes Ling wondered if he even remembered what it was like to see green or blue.

"Oh, don't be so melodramatic, kiddo," the saccharine voice echoed around him.

"Hey, I thought _you_ out of all people would understand," Ling retorted. "Your greed wouldn't allow you to tolerate a world filled with only two colours, would it?"

"Ha! I have no time for superficial things such as colour. I want women, money–"

"Power, yadda yadda yadda," Ling mumbled over him.

Greed only snorted, and his phantom face renting space beside Ling's body stretched into a wide grin. "You know so well, because you want exactly the same thing."

Ling rolled his eyes. "I know so well, because you can't quit _talking about it!_" And he crossed his arms and closed his eyes, signaling that he was done talking.

He had gotten used to keeping his thoughts from floating out into his and Greed's shared vicinity; it took a lot of concentration that only those trained in extreme meditation could have the will to do so, and it wasn't the first time he'd thanked Fu for teaching him. But there was no way to stop Greed's inner ruminations from reverberating around him, and if he wasn't careful, sometimes he'd find himself the unwilling audience to Greed's fantasies.

It unnerved him to think what Greed himself had been privy to when Ling was asleep; his dreams, after all, were also visions in and of themselves, and where was his meditative will when he's sleeping?

"Don't worry. There ain't nothing about that girl that I haven't seen before," Greed cackled, surprising Ling into realizing that he had not guarded his mind.

Ling didn't have to ask who he was talking about. He let the insult slide – both of them, for there had been two rolled in one. Who cared if Greed had been with hundreds of women in his lifetime? Who cared if Ling had never known Lan Fan that way? Greed had little to boast; wanting could only get you so far. Ling, of all people, knew that even at his age. Greed would never know satisfaction; never know the peace of sunrise on temple rooftops, the exhilaration of breathless sprints during training, the pride of overcoming terror.

Ling pitied him in a way. But he would never let the homunculus know that. So he smiled.

-o-

The man who took them in was balding and limping, but he told them he didn't need his hair nor his legs to make automail. And he made damn good automail.

They didn't really have a lot of choices. Lan Fan, much to her mortification, had fainted twice since leaving Dr. Knox. She apologized profusely to her grandfather, who had to carry her to a sanctuary, but he only ordered her to eat and rest. She could feel his disappointment, his shame, and she wondered briefly if it had been better had they gone with someone else.

The old automail engineer lived n the outskirts of the city, so far out that there had been no other houses for miles when they encountered him. He accepted humble payment: meat from the badlands animals, trade with the nearest village, more wood to re-stock his now almost empty stack of fire food. Fu had no trouble hunting, and the nearest village was only a few hours travel for him without Lan Fan hindering him, and chopping wood was as easy as breathing. They still paid him a small sum which the engineer did not refuse.

Lan Fan had a difficult time keeping track of the passing days the way she normally would, so when she woke up, she always asked how long she'd been asleep. Then she would count backwards. A hundred and twenty days since _the incident_, the scent of blood was still her best friend. Her arm socket was a ridiculous mess of nerves and flesh – recently sliced to accommodate the metal plate that would connect the automail with the rest of her body.

She lay in bed, her fever spiking up again. Her grandfather had just returned from an errand, and he sat on her right side, the side that sometimes could let him forget.

"Do you want some water?"

She shook her head.

The silence that enveloped them was thick and smoky. Her family had never been people of words, and she knew she should have been used to it, but there was a weight in this silence that made it unbearable. Still, she was afraid to speak first. _Those who know do not speak, and those who speak do not know._ She turned her head, and ached strongly for the Young Master, who spoke with abandon and was never more of a fool for it.

"I am proud of you," Fu whispered, and Lan Fan looked at him so quickly she felt a flash of pain on her shoulder. "And the Young Lord is too, I'm sure. If he's not, then he's an idiot."

And they both knew that Ling Yao was a lot of things, but he was not an idiot. Not anymore.

-o-

Ling wasn't prepared when the letters came. One offered the Siqi pass. Another's bribe was to relinquish its claim on their border mines. Each one came with lavish promises: gold, land, rare natural resources, trade agreements, political barters.

He buried his head in his hands, combing away the bangs from his face. The crown made his temples ache, and his neck felt the weight of extra five pounds for eight hours. When Lan Fan came closer to his desk, he knew that she had felt his agitation.

"Your Majesty?"

"Sit down," he told her. "And remove your mask." He saw the glint of surprise in her eyes. He'd hardly ever asked her to sit with him, not when she was a guard. But she was not, at least not for the next few minutes. She was his audience, a private one.

"There is a bid," he said simply, and even though the subject made bile rise to his throat, he could not suppress the amusement that tugged his lips and crinkled the corners of his eyes. "For _your hand in marriage._"

He laughed at the horror on her face, even though he could not remember ever having seen such a look on her before. Perhaps that was what she'd looked like when she received the news of him taking in Greed. Like he had gone insane. And sure enough, he didn't know why he was laughing, when his heart felt as heavy as Gluttony. Maybe he really was insane.

It made sense, in hindsight, the marriage proposals. In the past two years, he'd insisted that he had no time yet to take brides. So the men in power became impatient. If Ling would not take their women, they would take his. After all, to have the woman who spent every hour of every day at the Emperor's side as one's wife...

"Oh don't look like that, Lan Fan!" he teased, and selected one of the letters from the pile. He shook it before her. "Most of them don't even want you as a wife in duty. Only in name." Of course, because taking her away from her job would diminish the worth they see in her. But marriage still had laws to abide and terms to follow. These men were after only one thing. "General Wu said you only had to visit his home once every month or so. No wifely duties required. I think he's scared."

He couldn't help laughing harder at the frown that coloured her face, her eyes becoming glassy with either embarrassment or terror. He picked another one of the letters, this one with curvy calligraphy and mahogany rollers at each end. "The Zhao chief's second cousin even said he didn't mind polyandry so long as it's kept to four or less! Would you look at that?"

Lan Fan's face scrunched up in disgust. Then she scooted closer to the low table. She bent down, touching her head to the floor, and when she spoke, Ling heard the worry and anxiety in her voice. She'd never been good at masking her emotions by herself, even with ceramic on her face.

"Your Majesty, I promise... I will work harder. Sleep less if I can afford it, train more. I promise I will better–"

"Lan Fan!" he called, and she stopped, lifting her head to slide a wary glance at him. He leaned forward, and even though he wasn't supposed to, not as king, not as emperor, he cradled her cheek with his hand. "Have a little more faith in me, won't you? I won't give you away."

-o-

Well, at least the Emperor seemed to be having some fun over this. The bids were the last thing she could have predicted. Usually it was the women who had to drive themselves mad with desperation at the matchmakers, but the bids...

And amidst it all, even more overwhelming than the riches they offered, was _thinking_ she was worth that much. But was she really? The Siqi pass was a strategic location that the Yaos would benefit from immensely. Even _she_ was tempted to let the emperor take that bribe. She seemed a cheap price to pay for something like that.

"Don't underestimate your worth," the emperor whispered, as they traversed the hall that led to his room. It was about time he retired for the night. Though he was as much a warrior as she was, she couldn't help but notice the deepening shadows under his eyes, and the way he held his head as if he was about to nod off anytime soon. And unlike her, he had more than one thing vying for his attention during waking hours.

She blushed, wondering what it was about her that made him know what she felt, what she thought. It was unnerving and relieving. Unnerving to realize she would never be able to keep anything from him, relieving to know that she'd never have to utter a single word to tell him. Because she had to admit, words had never been her forte, even after all these years. One would think it would have rubbed off on her after spending so much time with Ling Yao.

"It is not _my_ worth," she said quietly. "It's what I know."

"Knowledge comes with a steep price. Some would kill for it."

She followed him to his apartments, where she would have to wait half an hour or so before the night shift guard would take over. Before he shut the door to his sleeping chamber, she stopped him, reluctant.

"Your Majesty, if you have to..."

"Lan Fan, don't."

"It's my duty."

He smiled, his eyes gentle and searing at the same time in the way only he could do. "Then it's my duty to make sure I would never have to."

She allowed herself to return his smile. "And here I thought marriage was _your_ problem."

He let out a hearty laugh. "Imagine if we marry each other. All these problems would go away." He closed the door gently, but not before Lan Fan caught the devious look on his face, the conspiratorial wink he sent her way as his face disappeared on the other side of the wood.

He was joking, Lan Fan was certain of that. Just teasing. These problems might disappear, but how many more would take their place?

Even so, she could not help the heat that crept to her cheeks and the lightness that enveloped her heart. Nighttime, after all, was a time for dreams.

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AN: I know this is for shippy day, but I cannot write romance to save my life. So if this is a little dry, I'm really really sorry! I really do wish that Ling and Lan Fan end up together eventually.

Oh, and this is also unbeta'd, so if there are any glaring mistakes, let me know. I'd love to hear feedback. Seriously, let me know what you think!


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